Gold's Latin name, "aurum," which translate to "glowing dawn," implies gold's natural yellow color. Gold is one of only two colored metal elements, the other being copper. All other metals are silver or gray. Gold in its purest state (24-karat) is too malleable for jewelry, so additional metals need to be added to it to make it stronger. These metals are typically copper, zinc, silver or palladium depending on the desired effect to the gold. How vibrant gold jewelry is depends on the type and amount of metal the gold is mixed with. A 9-karat gold ring will look significantly different than an 18-karat gold ring because the latter has twice as much pure gold in it. Gold was first used in jewelry over 5,000 years ago. One of the most popular metals throughout history, gold is still the most popular choice for wedding bands and engagement rings today. Though it has been popular for thousands of years gold is still extremely rare. It is estimated only 165,000 metric tonnes of gold have been mined throughout history with over 90% of the world's gold mined since the California Gold Rush. Today 60% of all mined gold becomes jewelry.